This invention relates to a resist composition containing a specific cross-linking agent useful in the production of semiconductor devices, etc., a process for forming a pattern using the resist composition, and a cross-linking agent for a negative working resist material using ArF excimer laser beams.
Recently, with an increase of integration of semiconductor integrated circuits, the minimum pattern in the integrated circuits becomes submicron order and this tendency is further advancing to more minimized one. It is a photolithography technique that plays an important role in the formation of fine patterns in the production of semiconductor devices.
Generally speaking, a resolution degree R of a resist in a reduced projective method is shown by the equation of Rayleigh: R=kxc2x7xcex/NA (wherein xcex is a wavelength of light from an exposure source, NA is a numerical aperture of a lens, and k is a process constant). As is clear from this equation, it is understood that in advance of minimization, the resolution degree of a resist can be increased proportionally, when a more shortened wavelength of light from the exposure source is used. By applying this, at present, an ultra LSI has been produced by an exposure technique using i-line light (wavelength of 365 nm) and KrF excimer laser beams (wavelength of 248 nm) as an exposure source, and further an exposure technique using ArF excimer laser beams (wavelength of 193 nm) as an exposure source has been developed in order to comply with still further minimized processing.
In order to form a pattern of submicron order with the use of an exposure light having more shortened wavelength such as deep UV light and one belonging to an area of vacuum UV, a resist used is required to have excellent transmittance against the wavelength of the exposure light and further to have excellent dry etching resistance. However, so far known resist materials have such a defect in that they show high absorbance against ArF excimer laser beams and hardly transmit the laser beams because they contain an aromatic ring such as phenol in its molecule, resulting in failing to form a fine pattern.
Under such a situation, resist materials containing no aromatic ring, having high transmittance against ArF excimer laser beams and high dry etching resistance have been developed. For instance, it is reported in JP-A 9-73173 and JP-A 8-259626 that resist materials wherein methacrylic acid is used as a base resin and an alicyclic ring is introduced show high transmittance and high dry etching resistance and thus can form a fine pattern of 0.2 xcexcm or less. However, all of these resist materials as mentioned above belong to positive type resist in which the part (or area) exposed to a light is dissolved in a developing solution.
On the other hand, a Levenson type phase shift method using a phase of light has been developed in i-line light lithography and KrF excimer laser lithography as an ultra resolution technique in compliance with minimization beyond the resolution limit of light. This technique is considered to be applied also to ArF excimer laser lithography. However, the Levenson type phase shift technique requires a negative type resist process because of a structure of a mask and cannot be applied to so far developed positive type resists.
Additionally, so far known negative type resists generally comprise as a matrix polymer a resin containing a benzene ring such as novolac resin and polyvinyl phenol and a triazine type compound as a cross-linking agent. Further, a resist using an epoxy group has been proposed as disclosed in Willard Conley, et al, Proc. SPIE, vol. 1262, 49 (1990). However, since a phenol resin is used as a matrix polymer, there is such a defect in that ArF excimer laser beams cannot be used because of its high absorbability to ArF excimer laser beams.
As mentioned above, a combination of the ArF excimer laser beams exposure technique with the Levenson type phase shift method seems to be very effective for the minimization, but there has been a problem in that no negative type resist applicable thereto has been developed yet and thus no negative type pattern can be formed.
Under such circumstances as mentioned above, the present invention has been accomplished to overcome the defects of prior art.
An object of the present invention is to provide a novel resist composition capable of giving a resist film which shows high transmittance of deep UV light having such a short wavelength as 220 nm or less and excellent etching resistance and thus can be applied to ArF excimer laser lithography using the Levenson type phase shift method, to provide a process for forming a pattern using this resist composition and to provide a novel cross-linking agent for an ArF negative type resist material.
The present invention provides a resist composition comprising
(a) an aliphatic alkali-soluble polymer,
(b) a compound represented by the following formula [1], [2] or [3],
(c) a photo-sensitive compound which generates an acid upon exposure to light, and
(d) a solvent capable of dissolving the- above components (a) to (c);
A1xe2x80x94T1xe2x80x94R1xe2x80x94T2xe2x80x94A2xe2x80x83xe2x80x83[1]
wherein R1 is a divalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94; A1 and A2 are independently an alkyl group containing one or more oxirane rings; and T1 and T2 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94, 
wherein R2 is a trivalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COO xe2x80x94 and xe2x80x94OCOxe2x80x94; A1 to A3 are independently an alkyl group containing one or more oxirane rings; and T1 to T3 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94, 
wherein R3 is a tetravalent hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94; A1 to A4 are independently an alkyl group containing one or more oxirane rings; and T1 to T4 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94.
The present invention also provides a process for forming a pattern, which comprises
a step of applying a resist composition described above to a substrate,
a step of subjecting the resulting substrate to heat treatment and then exposure to light having a wavelength of 220 nm or less through a mask, and
a step of developing the thus treated substrate using a developing solution, if necessary, after baking treatment.
The present invention further provides a cross-linking agent for an ArF negative working resist material, comprising a compound represented by the following formula [1], [2] or [3]:
A1xe2x80x94T1xe2x80x94R1xe2x80x94T2xe2x80x94A2xe2x80x83xe2x80x83[1]
wherein R1, A1, A2, T1 and T2 are as defined above, 
wherein R2, A1, A2, A3, T1, T2 and T3 are as defined above, 
wherein R3, A1, A2, A3, A4, T1, T2, T3 and T4 are as defined above.
The present invention still further provides a compound represented by the formula: 
wherein R2, A1, A2, A3, T1, T2 and T3 are as defined above, except for a case wherein R2 is 
each of T1 to T3 is xe2x80x94Oxe2x80x94; and each of A1 to A3 is a glycidyl group.
The present inventors have made extensive study for realizing the above-mentioned objects to find that when the compound of the formula [1], [2] or [3] is used as a cross-linking agent, a resist composition showing high photo-transparency in a wavelength range of 220 nm or less and capable of forming a fine negative type pattern can be obtained, and have accomplished the present invention on the basis of this finding.
The resist composition of the present invention comprises
(a) an aliphatic alkali-soluble polymer,
(b) a compound represented by the formula:
A1xe2x80x94T1xe2x80x94R1xe2x80x94T2xe2x80x94A2xe2x80x83xe2x80x83[1]
wherein R1 is a divalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94; A1 and A2 are independently an alkyl group containing one or more oxirane rings; and T1 and T2 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94, 
wherein R2 is a trivalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94; A1 to A3 are independently an alkyl group containing one or more oxirane rings; and T1 to T3 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94, or 
wherein R3 is a tetravalent hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94; A1 to A4 are independently an alkyl group containing one or more oxirane rings; and T1 to T4 are independently, xe2x80x94Oxe2x80x94, xe2x80x94COOxe2x80x94 or xe2x80x94OCOxe2x80x94,
(c) a photosensitive compound which generates an acid upon exposure to light, and
(d) a solvent capable of dissolving the above components (a) to (c).
The aliphatic alkali-soluble polymer in this invention means alkali-soluble polymers containing substantially no aromatic group in the polymer chain.
In the formula [1], R1 is a divalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94, said divalent aliphatic hydrocarbon residue including any of straight chained, branched and cyclic ones.
The straight chained and branched divalent aliphatic hydrocarbon residue includes one having 1 to 6 carbon atoms. Examples of such groups are a methylene group, an ethylidene group, a 1,2-ethane-di-yl group, a propylidene group, a 1,2-propane-di-yl group, a 1,3-propane-di-yl group, an isopropylidene group, a butylidene group, a 1,2-butane-di-yl group, a 1,3-butane-di-yl group, a 1,4-butane-di-yl group, a 2-methyl-1,2-propane-di-yl group, a 2-methyl-1,3-propane-di-yl group, a pentylidene group, a 1,2-pentane-di-yl group, a 1,4-pentane-di-yl group, a 1,5-pentane-di-yl group, a 2,3-pentane-di-yl group, a 2,4-pentane-di-yl group, a 2-methyl-2-butane-di-yl group, a 2-methyl-, 3-butane-di-yl group, a 2-methyl-1,4-butane-di-yl group, a 2-methyl-1,5-butane- di-yl group, a 2- methyl-2,3-butane-di-yl group, a 2-methyl-2,4-butane-di-yl group, a 2,2-dimethyl-1,3-propane-di-yl group, a heyxlidene group, a 1,2-hexane-di-yl group, a 1,3-hexane-di-yl group, a 1,4-hexane-di-yl group, a 1,5-hexane-di-yl group, a 1,6-hexane-di-yl group, a 2,3-hexane-di-yl group, a 2,4-hexane-di-yl group, a 3,4-hexane-di-yl group, etc. Among them, those having 1 to 4 carbon atoms are preferable.
The cyclic divalent aliphatic hydrocarbon residue includes one having 3 to 7 carbon atoms. Examples of such groups are a 1,2-cyclopropane-di-yl group, a 1,2-cyclobutane-di-yl group, a 1,3-cyclobutane-di-yl group, a 1,2-cyclopentane-di-yl group, a 1,3-cyclopentane-di-yl group, a 1,2-cyclohexane-di-yl group, a 1,3-cyclohexane-di-yl group, a 1,4-cyclohexane-di-yl group, a 1,2-cycloheptane-di-yl group, a 1,3-cycloheptane-di-yl group, a 1,4-cycloheptane-di-yl group, etc. Among them, those having 5 to 7 carbon atoms are preferable.
Specific examples of the divalent aliphatic hydrocarbon residue containing at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94are those containing 1 to 5, preferably 1 to 3 xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and/or xe2x80x94OCOxe2x80x94 groups therein. Examples of such groups are shown by the following formulae [4] to [10]:
xe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[4]
xe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[5]
xe2x80x94Q1xe2x80x94OCOxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[6]
xe2x80x94Q1xe2x80x94COxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[7]
xe2x80x94Q1xe2x80x94COOxe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94OCOxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[8]
xe2x80x94Q1xe2x80x94OCOxe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94COOxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[9]
xe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94COxe2x80x94Q1xe2x80x94Oxe2x80x94Q1xe2x80x94xe2x80x83xe2x80x83[10]
wherein Q1 is a divalent aliphatic hydrocarbon residue.
The divalent aliphatic hydrocarbon residue shown by Q1 in the formulae [4] to [10] has the same meaning as one mentioned above referring to R1 in the formula [1].
The trivalent aliphatic hydrocarbon residue in the trivalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94, which is shown by R2 in the formula [2], may be any of straight chained, branched and cyclic ones.
The straight chained and branched trivalent aliphatic hydrocarbon residue includes one having 1 to 6 carbon atoms. Examples of such groups are a methine group, an ethylidyne group, a 1-ethanyl-2-ylidene group, a propylidyne group, a 2-propanyl-3-ylidene group, a 1-propanyl-3-ylidene group, a 1-propanyl-2-ylidene group, a 1,2,3-propane-tri-yl group, a butylidyne group, a 3-butanyl-4-ylidene group, a 2-butanyl-4-ylidene group, a 1-butanyl-4-ylidene group, a 1-butanyl-2-ylidene group, a 1,2,3-butan-tri-yl group, a 1,2,4-butane-tri-yl group, a 2-butanyl-3-ylidene group, a 1-butanyl-3-ylidene group, a 2-methylpropylidine group, a 2-methyl-2-propanyl-l-ylidene group, a 2-methyl-1,2,3-propane-tri-yl group, a 2-methyl-1,3,1xe2x80x2-propane-tri-yl group, a pentylidyne group, a 4-pentanyl-5-ylidene group, a 3-pentanyl-5-ylidene group, a 2-pentanyl-5-ylidene group, a 1-pentanyl-5-ylidene group, a 1-pentanyl-2-ylidene group, a 1,2,3-pentane-tri-yl group, a 1,2,4-pentane-tri-yl group, a 1,2,5-pentane-tri-yl group, a 1-pentanyl-3-ylidene group, a 1,3,4-pentane-tri-yl group, a 1,3,5-pentane-tri-yl group, a 3-pentanyl-4-ylidene group, a 2-pentanyl-4-ylidene group, a 1-pentanyl-4-ylidene group, a 2-pentanyl-3-ylidene group, a 2-methylbutylidyne group, a 4-methyl-4-butanyl-5-ylidene group, a 4-methyl-3-butanyl-5-ylidene group, a 4-methyl-2-butanyl-5-ylidene group, a 4-methyl-1-butanyl-5-ylidene group, a 2-methyl-1,2,3-tributane-tri-yl group, a 2-methyl-1,2,4-butane-tri-yl group, a 3-methyl-3-butanyl-4-ylidene group, a 2,2,-dimethylpropylidyne group, a 2,2,-dimethyl-1-propanyl-3-ylidene group, a 2,2-dimethyl-1,3,1xe2x80x2-propane-tri-yl group, a hexylidyne group, a 5-hexanyl-6-ylidene group, a 4-hexanyl-6-ylidene group, a 3-hexanyl-6-ylidene group, a 2-hexanyl-6-ylidene group, a 1-hexanyl-6-ylidene group, a 1,2,3-hexane-tri-yl group, a 1,2,4-hexane-tri-yl group, a 1,2,5-hexane-tri-yl group, a 1,2,6-hexane-tri-yl group, a 1-hexanyl-3-ylidene group, a 1,3,4-hexane-tri-yl group, a 1,3,5-hexane-tri-yl group, a 1,3,6-hexane-tri-yl group, a 4-hexanyl-5-ylidene group, a 3-hexanyl-5-ylidene group, a 2-hexanyl-5-ylidene group, a 1-hexanyl-5-ylidene group, a 2-hexanyl-3-ylidene group, a 2,3,4-hexane-tri-yl group, a 2,3,5-hexane-tri-yl group, a 2,3,6-hexane-tri-yl group, a 3-hexanyl-4-ylidene group, a 2-hexanyl-4-ylidene group, a 1-hexanyl-4-ylidene group, etc. Among them, those having 1 to 4 carbon atoms are preferable.
The cyclic trivalent aliphatic hydrocarbon residue includes one having 3 to 7 carbon atoms. Examples of such groups are a 1,2,3-cyclopropane-tri-yl group, a 1,2,3-cyclobutane-tri-yl group, a 1,2,3-cyclopentane-tri-yl group, a 1,2,4-cyclopentane-tri-yl group, a 1,2,3-cyclohexane-tri-yl group, a 1,2,4-cyclohexane-tri-yl group, a 1,2,5-cyclohexane-tri-yl group, a 1,3,5-cyclohexane-tri-yl group, a 1,2,3-cycloheptane-tri-yl group, a 1,2,4-cycloheptane-tri-yl group, a 1,2,5-cycloheptane-tri-yl group, a 1,3,4-cycloheptane-tri-yl group, a 1,3,5-cycloheptane-tri-yl group, etc. Among them, those having 5 to 7 carbon atoms are preferable.
Specific examples of the trivalent aliphatic hydrocarbon residue containing at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94 are those containing 1 to 5, preferably 1 to 3 groups selected from xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94 groups therein. Examples of the groups are shown by the following formulae [11] to [17]. 
wherein Q2 is a trivalent aliphatic hydrocarbon residue; and Q1 is as defined above.
The trivalent aliphatic hydrocarbon residue shown by Q2 in the formulae [11] to [17] has the same meaning as one mentioned above referring to R2 in the formula [2].
The tetravalent aliphatic hydrocarbon residue in the tetravalent aliphatic hydrocarbon residue which may contain at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94, which is shown by R3 in the formula [3], may be any of straight chained, branched and cyclic ones.
The straight chained and branched tetravalent aliphatic hydrocarbon residue includes one having 1 to 8 carbon atoms. Examples of such groups are a carbon atom, an ethane-di-ylidene group, a 1-ethanyl-2-ylidyne group, a propane-di-ylidene group, a 1-propanyl-3-ylidyne group, a 1,2-propane-di-yl-3-ylidene group, a 1,3-propane-di-yl-2-ylidene group, a butane-di-ylidene group, a 1,2-butane-di-yl-4-ylidene group, a 1,4-butane-di-yl-2-ylidene group, a 1,2,3,4-butane-tetra-yl group, a 2-methyl-1,2,3,1xe2x80x2-propane-tetra-yl group, a pentane-di-ylidene group, a 1,5-pentane-di-yl-2-ylidene group, a 1,5-pentane-di-yl-3-ylidene group, a 1-pentanyl-5-ylidyne group, a 1,2,3,4-pentane-tetra-yl group, a 1,2,3,5-pentane-tetra-yl group, a 2-methyl-1,2,3,4-butane-tetra-yl group, a 2-methyl-1,2,3,1xe2x80x2-butane-tetra-yl group, a 2-methyl-1,2,4,1xe2x80x2-butane-tetra-yl group, a 2,2-dimethyl-1,3,1xe2x80x2,1xe2x80x2-propane-tetra-yl group, a hexane-di-ylidene group, a 1,6-hexane-di-yl-2-ylidene group, a 1,6-hexane-di-yl-3-ylidene group, a 1-hexanyl-6-ylidyne group, a 1,2,3,4-hexane-tetra-yl group, a 1,2,3,5-hexane-tetra-yl group, a 1,2,3,6-hexane-tetra-yl group, a 1,2,4,5-hexane-tetra-yl group, etc. Among them, those having 4 to 7 carbon atoms are preferable.
The cyclic tetravalent aliphatic hydrocarbon residue includes one having 3 to 7 carbon atoms. Examples of such groups are a 1,2,3,4-cyclobutan-tetra-yl group, a 1,2,3,4-cyclopentane-tetra-yl group, a 1,2,3,4-cyclohexane-tetra-yl group, a 1,2,3,5-cyclohexane-tetra-yl group, a 1,4-cyclohexane-di-yl-2-ylidene group, a 1,3-cyclohexane-di-yl-5-ylidene group, a 1,2,3,4-cycloheptane-tetra-yl group, a 1,2,4,5-cycloheptane-tetra-yl group, a 1,2,3,5-cycloheptane-tetra-yl group, a 1,2,4,6-cycloheptane-tetra-yl group, a 1,3-cycloheptane-di-yl-5-ylidene group, a 1,2-cycloheptane-di-yl-4-ylidene group, etc. Among them, those having 5 to 7 carbon atoms are preferable.
Specific examples of the tetravalent aliphatic hydrocarbon residue containing at least one of xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and xe2x80x94OCOxe2x80x94 are those containing 1 to 5, preferably 1 to 3 xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94 and/or xe2x80x94OCOxe2x80x94 groups therein. Examples of the groups are shown by the following formulae [18] to [23]: 
wherein Q3 is a tetravalent aliphatic hydrocarbon residue; and Q1 is as defined above.
The tetravalent aliphatic hydrocarbon residue shown by Q3 in the formulae [18] to [23] has the same meaning as one mentioned above referring to R3 in the formula [3].
The alkyl group containing one or more oxirane rings shown by A1 and A2 in the formulae [1] to [3], shown by A3 in the formulae [2] and [3], and shown by A4 in the formula [4] includes one containing 1 to 3 oxirane rings at terminal position(s) and/or at internal position(s) thereof. These alkyl groups include straight-chained, branched and cyclic. Among these alkyl groups, a cycloalkyl group containing one or more oxirane rings is preferable. Examples of such alkyl groups are those represented by the formula: 
wherein E1 and E2 are independently a lower alkylene group; a and b are independently 0 or 1; and n is 1 to 3, or by the formula: 
wherein y is 3 to 5.
The lower alkylene group shown by E1 and E2 in the formula [24] may be straight-chained or branched, including one preferably having 1 to 6 carbon atoms. Examples of these alkylene groups are a methylene group, an ethylene group, a propylene group, a butylene group, a 2-methylpropylene group, a pentylene group, a 2,2-dimethylpropylene group, a 2-ethylpropylene group, a hexylene group, etc.
The specific examples of the alkyl group containing one or more oxirane rings represented by the formula [24] are an epoxy ethyl group, a 2,3-epoxy propyl group (a glycidyl group), a 2,3-epoxy butyl group, a 3,4-epoxy butyl group, a 2,3-epoxy pentyl group, a 3,4-epoxy pentyl group, a 4,5-epoxy pentyl group, a 2,3-, 4,5-diepoxy pentyl group, a 2,3-epoxy hexyl group, a 3,4-epoxy hexyl group, a 4,5-epoxy hexyl group, a 5,6-epoxy hexyl group, a 2,3-, 4,5-diepoxy hexyl group, a 2,3-,5,6-diepoxy hexyl group, a 3,4-, 5,6-diepoxy hexyl group, a 2,3-epoxy heptyl group, a 3,4-epoxy heptyl group, a 4,5-epoxy heptyl group, a 5,6-epoxy heptyl group, a 6,7-epoxy heptyl group, a 2,3-, 4,5-diepoxy heptyl group, a 2,3-, 5,6-diepoxy heptyl group, a 2,3-, 6,7-diepoxy heptyl group, a 3,4-, 5,6-diepoxy heptyl group, a 3,4-, 6,7-diepoxy heptyl group, a 2,3-, 4,5-, 6,7-triepoxy heptyl group, a 1-methyl-2,3-epoxy propyl group, a 2-methyl-2,3-epoxy propyl group, a 1-methyl-2,3-epoxy butyl group, a 3-methyl-3,4-epoxy butyl group, a 1-methyl-2,3-epoxy pentyl group, a 1-methyl-4,5-epoxy pentyl group, a 2-methyl-2,3-epoxy pentyl group, a 2-methyl-4,5-epoxy pentyl group, a 3-methyl-3,4-epoxy pentyl group, a 4-methyl-2,3-epoxy pentyl group, a 4-methyl-3,4-epoxy pentyl group, a 4-methyl-4,5-epoxy pentyl group, a 1-methyl-2,3-epoxy hexyl group, a 2-methyl-3,4-epoxy hexyl group, a 2-methyl-5,6-epoxy hexyl group, a 3-methyl-5,6-epoxy hexyl group, a 4-methyl-2,3-epoxy hexyl group, a 4-methyl-5,6-epoxy hexyl group, a 1-methyl-2,3-, 4,5-diepoxy pentyl group, a 2-methyl-2,3-, 4,5-diepoxy pentyl group, etc.
The specific examples of the alkyl group containing one or more oxirane rings represented by the formula [25] are a 2,3-epoxy cyclopentyl group, a 3,4-epoxy cyclopentyl group, a 2,3-epoxy cyclohexyl group, a 3,4-epoxy cyclohexyl group, a 2,3-epoxy cycloheptyl group, a 3,4-epoxy cycloheptyl group, a 4,5-epoxy dicycloheptyl group, etc.
The cross-linking agent for ArF negative resist material of the present invention represented by the formulae [1] to [3] can be obtained, for example, by the following preparation methods (a) to (c).
Method (a):
The desired compound can be obtained by reacting a compound of the formula:
R4(OH)mxe2x80x83xe2x80x83[26]
wherein R4 is a divalent aliphatic hydrocarbon residue, a trivalent aliphatic hydrocarbon residue or a tetravalent aliphatic hydrocarbon residue; and m is 2 to 4, with a compound of the formula:
R5xe2x80x94Xxe2x80x83xe2x80x83[27]
wherein R5 is an alkyl group containing at least one oxirane ring; X is a halogen atom, xe2x80x94COXxe2x80x2 (wherein Xxe2x80x2 is a halogen atom) or a group which is capable of forming a conjugate base of a strong acid by elimination, if necessary in a suitable solvent, and in the presence of a basic catalyst.
In the formula [26], the divalent aliphatic hydrocarbon residue shown by R4 has the same meaning as one mentioned above referring to R1 in the formula [1], the trivalent aliphatic hydrocarbon residue shown by R4 has the same meaning as one mentioned above referring to R2 in the formula [2], and the tetravalent aliphatic hydrocarbon residue shown by R4 has the same meaning as one mentioned above referring to R3 in the formula [3].
The alkyl group containing at least one oxirane ring shown by R5 in the formula [27] has the same meaning as in the formula [24] or [25]. The halogen atom shown by X and Xxe2x80x2 includes fluorine, chlorine, bromine, iodine, etc. The group which is capable of forming a conjugate base of strong acid by elimination shown by X includes, for example, a p-toluenesulfonyloxy group, a methanesulfonyloxy group, a trifluoromethanesulfonyloxy group, etc.
The basic catalyst includes an organic amine such as triethylamine, diisopropylethylamine, N,N-dimethylaniline, piperidine, pyridine, 4-dimethylamino-pyridine, 1,5-diazobicyclo[4,3,0]non-5-ene, 1,8-diazabicyclo [5,4,0]undec-7-ene, tri-n-butylamine and N-methylmorpholine; and an alkali metal hydroxide such as sodium hydroxide and potassium hydroxide.
The amount of the basic catalyst to be used is not specifically limited and can suitably be selected from the range of 0.1 to 20 moles preferably 1 to 10 moles per mole of the compound of the formula [26].
The solvent which is used upon necessity includes hydrocarbons such as toluene, xylene, benzene, cyclohexane, n-hexane and n-octane; halogenated hydrocarbons such as methylene chloride, dichloroethane and trichloroethylene; esters such as methyl acetate, ethyl acetate, n-butyl acetate and methyl propionate; ethers such as dimethyl ether, diethyl ether, diisopropyl ether, dimethoxyethane, tetrahydrofuran and dioxane; N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethyl-acetamide, dimethylsulfoxide, water, etc., which may be used alone or in a suitable combination of two or more thereof.
When water or water together with a solvent causing phase separation from water is used as the solvent, the reaction may be conducted, if necessary, with the use of a phase-transfer catalyst such as tetra-n-butylammonium bromide, benzyltriethylammonium chloride, benzyltriethylammonium bromide, benzyltrimethylammonium bromide and methyltrioctylammonium chloride including commercially available ones having Brand Name of Aliquat 336 and Adogen 464 from Aldrich Chemical Co., Inc.
The amount of the phase-transfer catalyst to be used is not specifically limited and generally selected from the range of 0.1 to 50 mole %, preferably 0.1 to 20 mole % based on the amount of the compound of the formula [26].
The amount of the compound of the formula [27] to be used is not specifically limited and can suitably be selected from the range of 1 to 30 moles, preferably 2 to 10 moles per mole of the compound of the formula [26]. The compound of the formula [27] may be used alone or as a mixture thereof.
The reaction temperature is not specifically limited and selected generally from the range of 0 to 150xc2x0 C., preferably 20 to 80xc2x0 C.
The reaction time depends upon the kind of the compound of the formula [26] and such reaction conditions as concentration of the compound and is generally selected from the range of 0.5 to 48 hours.
Method (b):
The desired compound can be obtained by reacting a compound of the formula:
R4(X)pxe2x80x83xe2x80x83[28]
wherein p is 2 to 4; and R4 and X are as defined above, with a compound of the formula:
R5xe2x80x94OHxe2x80x83xe2x80x83[29]
wherein R5 is as defined above, in the presence of a basic catalyst and, if necessary, in a suitable solvent.
The basic catalyst, the solvent which is used upon necessity and the phase-transfer catalyst which is used upon necessity in case of using water or water together with a solvent causing phase separation from water are the same ones as mentioned in the Method (a).
The amount of the basic catalyst to be used is not specifically limited and can suitably be selected from the range of 0.1 to 20 moles, preferably 1 to 10 moles per mole of the compound of the formula [28].
The amount of the phase-transfer catalyst to be used is not specifically limited and can suitably be selected from the range of 0.1 to 50 mole %, preferably 0.1 to 20 mole % based on the amount of the compound of the formula [28].
The amount of the compound of the formula [29] to be used is not specifically limited and can suitably be selected from the range of 1 to 30 moles, preferably 2 to 10 moles per mole of the compound of the formula [28]. The compound of the formula [29] may be used alone or as a mixture thereof.
The reaction temperature is not specifically limited and selected generally from the range of 0 to 150xc2x0 C., preferably 20 to 80xc2x0 C.
The reaction time depends upon the kind of the compound of the formula [28] and such reaction conditions as concentration of the compound and is generally selected from the range of 0.5 to 48 hours.
Method (c):
The desired compound can be obtained by subjecting a compound of the formula:
B1xe2x80x94T1xe2x80x94R1xe2x80x94T2xe2x80x94B2xe2x80x83xe2x80x83[30]
wherein B1 and B2 are independently an aliphatic unsaturated hydrocarbon group containing at least one double bond; and T1, T2 and R1 are as defined above, a compound of the formula:

wherein B1 to B3 are independently an aliphatic unsaturated hydrocarbon group containing at least one double bond; and T1 to T3 and R2 are as defined above, or a compound of the formula: 
wherein B1 to B4 are independently an aliphatic unsaturated hydrocarbon group containing at least one double bond; and T1 to T4 and R3 are as defined above, to a reaction in the presence of an oxidizing agent, if necessary, in the presence of a suitable solvent.
The aliphatic unsaturated hydrocarbon group containing at least one double bond shown by B1 to B4 in the above formulas includes one containing 1 to 3 double bonds at a terminal position and/or suitable internal position(s) thereof. The aliphatic unsaturated hydrocarbon group mentioned above includes one having 2 to 14 carbon atoms. Specific examples thereof are an ethenyl group, a propenyl group, a 2-butenyl group, a 3-butenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 2,4-pentane-di-enyl group, a 2-hexenyl group, a 3-hexenyl group, a 4-hexenyl group, a 5-hexenyl group, a 2,4-hexane-di-enyl group, a 2,5-hexane-di-enyl group, a 3,5-hexane-di-enyl group, a 2-heptenyl group, a 3-heptenyl group, a 4-heptenyl group, a 5-heptenyl group, a 6-heptenyl group, a 2,4-heptane-di-enyl group, a 2,5-heptane-di-enyl group, a 2,6-heptane-di-enyl group, a 3,5-heptane-di-enyl group, a 3,6-heptane-di-enyl group, a 2,4,6-heptane-tri-enyl group, a 1-methyl-2-propenyl group, a 2-methyl-2-propenyl group, a 1-methyl-2-butenyl group, a 3-methyl-3-butenyl group, a 1-methyl-2-pentenyl group, a 1-methyl-4-pentenyl group, a 2-methyl-2-pentenyl group, a 2-methyl-4-pentenyl group, a 3-methyl-3-pentenyl group, a 4-methyl-2-pentenyl group, a 4-methyl-3-pentenyl group, a 4-methyl-4-pentenyl group, a 1-methyl-2-hexenyl group, a 2-methyl-3-hexenyl group, a 2-methyl-5-hexenyl group, a 3-methyl-5-hexenyl group, a 4-methyl-2-hexenyl group, a 4-methyl-5-hexenyl group, a 1-methyl-2,4-pentane-di-enyl group, a 2-methyl-2,4-pentane-di-enyl group, an octenyl group, a dodecanyl group, a 2-cyclopenten-1-yl group, a 3-cyclopenten-1-yl group, a 2-cyclohexen-1-yl group, a 3-cyclohexen-1-yl group, a 2-cyclohepten-1-yl group, a 3-cyclohepten-1-yl group, a 4-cyclohepten-1-yl group, a 2-cycloocten-1-yl group, etc.
The oxidizing agent includes an inorganic peroxide such as hydrogen peroxide and sodium perborate; an organic peroxide such as peracetic acid, perpropionic acid, perbenzoic acid and m-chloroperbenzoic acid, etc.
The amount of the oxidizing agent to be used is not specifically limited and can suitably be selected from the range of 0.1 to 20 moles, preferably 1 to 10 moles per mole of the compound of the formula [30], [31] or [32].
The solvent which is used upon necessity includes hydrocarbons such as toluene, xylene, benzene, cyclohexane, n-hexane and n-octane; halogenated hydrocarbons such as methylene chloride, dichloroethane and trichloroethylene; esters such as methyl acetate, ethyl acetate, n-butyl acetate and methyl propionate; ethers such as dimethyl ether, diethyl ether, diisopropyl ether, dimethoxyethane, tetrahydrofuran and dioxane; N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, water, etc., which may be used alone or in a suitable combination of two or more thereof.
The reaction temperature is not specifically limited and selected generally from the range of 0 to 150xc2x0 C., preferably 20 to 80xc2x0 C.
The reaction time depends upon the kind of the compound of the formula [30], [31] or [32] and such reaction conditions as concentration of the compound and is generally selected from the range of 0.5 to 48 hours.
A treatment of the resultant after the reaction can be conducted according to a conventional manner, including purification and/or separation of the compound of the formula [1], [2] or [3] thus obtained by extraction, recrystallization, etc. After such a treatment as above, the resultant can be used as a material for the resist composition.
As the compounds of the formulae [26] to [32] which are used as the starting materials in the above-mentioned methods (a) to (c), commercially available ones may be used, or the compounds may be produced according to a conventional manner.
The cross-linking agent for the ArF negative working resist material of the present invention thus obtained (hereinafter, abbreviated as xe2x80x9cthe cross-linking agent of the present inventionxe2x80x9d) can provide the following effects. Namely, when it is used as a material in a resist composition together with an aliphatic alkali-soluble polymer, a cross-linking reaction between hydrophilic groups in the aliphatic alkali-soluble polymer on one hand and the cross-linking agent of the formula [1], [2] or [3] on the other hand is allowed to proceed by the act of an acid generated from a photoacid generator, whereby the polymer is made insoluble in an alkaline developing solution. On the other hand, no acid is generated on the part (or area) which is not exposed to light, and thus no cross-linking reaction is allowed to proceed on this non-light-exposed part even by heating, and therefore the polymer remains alkali-soluble. Consequently, there is caused a difference in solubility into an alkaline developing solution between the part exposed to light and the part not exposed to light, so that a well-contrasted negative type pattern is formed.
In this way, the resist composition containing an aliphatic alkali-soluble polymer, the above-mentioned cross-linking agent of the present invention, a photo-sensitive compound which generates an acid upon exposure to light and a solvent capable of dissolving those components can extraordinarily effectively be used as a resist material for ArF excimer laser beams which are expected as new photo-exposure technology belonging to the next generation.
The aliphatic alkali-soluble polymer in the resist composition of the present invention includes one comprising a monomer unit shown by the formula [33] as a structural component: 
wherein R6 is a hydrogen atom or a lower alkyl group; R7 is a hydrogen atom, a lower alkyl group, a cyano group, an alkyloxycarbonyl group or a carboxyl group; R8 is a hydrogen atom, a lower alkyl group, an alkyloxycarbonyl group or a carboxyl group; R9 is a hydrophilic group; and Z is a spacer; and R7 and Zxe2x80x94R9 may form together a group of xe2x80x94COxe2x80x94Oxe2x80x94COxe2x80x94 or xe2x80x94COxe2x80x94NHxe2x80x94COxe2x80x94.
In the formula [33], the lower alkyl group shown by R6 to R8 may be straight-chained or branched and includes those preferably having 1 to 6 carbon atoms. Examples of these alkyl groups are a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 3,3-dimethylbutyl group, a 1,1-dimethylbutyl group, a 1-methylpentyl group, an n-hexyl group, an isohexyl group, etc.
The alkyloxycarbonyl group shown by R7 and R8 may be straight-chained, branched or cyclic and may contain a double bond and includes those having 2 to 19 carbon atoms. Examples the alkyloxycarbonyl group are a methyloxycarbonyl group, an ethyloxycarbonyl group, a propyloxycarbonyl group, butyloxycarbonyl group, a pentyloxycarbonyl group, a hexyloxycarbonyl group, a heptyloxycarbonyl group, an octyloxycarbonyl group, a dodecyloxycarbonyl group, an octadecyloxycarbonyl group, a cyclohexyloxycarbonyl group, an ethenyloxycarbonyl group, a propenyloxycarbonyl group, a butenyloxycarbonyl group, a tert-butyloxycarbonyl group, a 2-ethyl-hexyloxycarbonyl group, etc.
The hydrophilic group shown by R9 includes a hydroxy group, a carboxyl group, a carbamoyl group, an amino group, a hydroxyalkyl group having 1 to 18 carbon atoms such as a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a hydroxypentyl group, a hydroxyhexyl group, a hydroxyheptyl group, a hydroxyoctyl group, a hydroxydodecyl group and a hydroxyoctadecyl group.
The spacer shown by Z includes a group of the formula:
xe2x80x94(COO)qxe2x80x94(R10)r(R11)s(R12)txe2x80x94xe2x80x83xe2x80x83[34]
wherein R11 is a divalent hydrocarbon residue which may contain at least one oxygen atom; R10 and R12 are independently a lower alkylene group; and q, r, s and t are independently 0 or 1, provided that when q is 1, s is 1.
The divalent hydrocarbon residue in the divalent hydrocarbon residue which may contain at least one oxygen atom shown by R11 in the formula [34] includes, for example, an alkylene group. The alkylene group may be straight-chained, branched or cyclic and includes those having 1 to 20 carbon atoms. Examples of such an alkylene group are a methylene group, an ethylene group, a propylene group, a butylene group, a 2-methylpropylene group, a pentylene group, a 2,2-dimethylpropylene group, 2-ethylpropylene group, a hexylene group, a heptylene group, an octylene group, a 2-ethylhexylene group, a nonylene group, a decylene group, a cyclopropylene group, a cyclopentylene group, a cyclohexylene group, an adamantane-di-yl group, a tricyclo[5,2,1,02.6]decane-di-yl group, a norbornane-di-yl group, a methylnorbornane-di-yl group, an isobornane-di-yl group, a decaline-di-yl group, etc., among which one having 1 to 10 carbon atoms is preferable.
The divalent hydrocarbon residue containing an oxygen atom includes one mentioned above which contains 1 or more, preferably 1 to 3 oxygen atoms in the chain of the hydrocarbon residue, which is specifically exemplified by a methoxyethylene group, an ethoxyethylene group, a bornyloxyethylethylene group, a norbornyloxyethylethylene group, a mentyloxyethylethylene group, a adamantyloxyethylethylene group, a methoxyethoxyethylethylene group, a ethoxyethoxyethylethylene group, a bornyloxyethoxyethylethylene group, a mentyloxyethoxyethylethylene group, xe2x80x94Oxe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2, xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, and xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94.
The lower alkylene group shown by R10 and R12 may be straight-chained or branched and includes those having 1 to 6 carbon atoms. Examples of such a lower alkylene group are a methylene group, an ethylene group, a propylene group, a butylene group, a 2-methylpropylene group, a pentylene group, a 2,2-dimethylpropylene group, a 2-ethylpropylene group, a hexylene group, etc.
The monomer unit represented by the formula [33] include one derived from a monomer of the formula: 
wherein R6 to R9 and Z are as defined above.
The specific examples of the monomers are those of the formulae: 
ethylenically unsaturated carboxylic acids having 3 to 20 carbon atoms such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, vinylacetic acid and allylacetic acid (these acids may form salts with an alkali metal such as sodium and potassium, or ammonium salts); ethylenically unsaturated carboxylic acid hydroxyalkyl esters having 4 to 20 carbon atoms such as 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate and 2-hydroxypropyl acrylate; ethylenically unsaturated amide or imide compounds having 3 to 20 carbon atoms such as acrylamide, methacrylamide and maleimide; ethylenically unsaturated aldehydes having 3 to 20 carbon atoms such as acrolein and crotonaldehyde. The aliphatic alkali-soluble polymer includes homopolymers derived from one and the same monomer mentioned above and copolymers derived from two or more different kinds of monomers mentioned above.
The aliphatic alkali-soluble polymer used in the present invention may contain other monomer units as a structural component so far as the monomer units do not make the whole polymer alkali-insoluble. The other monomer mentioned just above includes alkenyl esters having 3 to 20 carbon atoms such as vinyl formate, vinyl acetate, vinyl propionate and isopropenyl acetate; halogen-containing ethylenically unsaturated compounds having 2 to 20 carbon atoms such as vinyl chloride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene and tetrachloroethylene; ethylenically unsaturated carboxylic acid esters having 4 to 20 carbon atoms such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, vinyl methacrylate, allyl methacrylate, adamantyl methacrylate, tricyclodecanyl methacrylate, mentyl methacrylate, norbornyl methacrylate, isobornyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, vinyl acrylate, adamantyl acrylate, tricylodecanyl acrylate, mentyl acrylate, norbornyl acrylate, isobornyl acrylate, dimethyl itaconate, diethyl itaconate, dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, methyl crotonate, ethyl crotonate, vinyl crotonate, dimethyl citraconate, diethyl citraconate, dimethyl mesaconate, diethyl mesaconate and methyl 3-butenoate; cyano-containing ethylenically unsaturated compounds having 3 to 20 carbon atoms such as acrylonitrile, methacrylonitrile and allyl cyanide; ethylenically unsaturated amide compounds having 3 to 20 carbon atoms such as acrylamide, methacrylamide and maleimide; ethylenically unsaturated aldehydes having 3 to 20 carbon atoms such as acrolein and crotonaldehyde; ethylenically unsaturated aliphatic heterocyclic amines having 5 to 20 carbon atoms such as N-vinyl pyrrolidone and vinyl piperidine; ethylenically unsaturated alcohols having 3 to 20 carbon atoms such as allyl alcohol and crotyl alcohol; diene compounds having 4 to 20 carbon atoms such as butadiene and isoprene, etc. In the aliphatic alkali-soluble polymers, only one kind or two or more different kinds of monomer units derived from the above-mentioned monomers may be incorporated as a structural component.
As the above monomers, commercially available ones may be used or those produced according to a conventional method may be used. The specific examples of the aliphatic alkali-soluble polymer used in the present invention are those containing one or more segments represented by the following formulae: 
The photo-sensitive compound generating an acid upon exposure to light (hereinafter, abbreviated as xe2x80x9ca photoacid generatorxe2x80x9d) which is used in combination with the cross-linking agent of the present invention in the resist composition may be any of photo-sensitive compounds which generate an acid upon exposure to light and give no bad influence upon formation of a pattern. Among them, those which show high transmittance around a wavelength of 193 nm and maintain high transparency of a resist composition, or give enhanced transmittance around a wavelength of 193 nm upon exposure to light and maintain high transparency of a resist composition are particularly desirable.
Examples of such preferable photoacid generators include commercially available ones, that is, sulfonium salts such as trimethylsulfonium/trifluoromethane sulfonate, triphenylsulfonium/trifluoromethane sulfonate, cyclohexylmethyl(2-oxo-cyclohexyl)sulfonium/trifluoromethane sulfonate, cyclopentylmethyl(2-oxo-cyclohexyl)sulfonium/trifluoromethane sulfonate and 2-oxo-cyclohexylmethyl(2-norbornyl)sulfonium/tri-fluoromethane sulfonate; acid imides such as trifluoromethyl sulfonyloxy-7-oxabicyclo[2,2,1]hept-5-ene-2,3-dicarboxylimide, trifluoromethyl sulfonyloxy bicyclo[2,2,2]hept-5-ene-2,3-carboxylimide and trifluoromethyl sulfonyloxy succinimide; diazodisulfone compounds such as 1-cyclohexylsulfonyl-1-(1,1-dimethylethylsulfonyl)diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(1-methylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane, bis(tert-butylsulfonyl)diazomethane, tert-butylsulfonylmethyl sulfonyl diazomethane and cyclohexylsulfonyl ethylsulfonyl diazomethane.
The solvent used in the case of using the cross-linking agent of the present invention in the resist composition may be any of those capable of dissolving the cross-linking agent of the present invention, the aliphatic alkali-soluble polymer and the photoacid generator. Particularly, solvents improving good film-forming ability and having no absorbance around a wavelength of 190 to 400 nm are preferably used. Specific examples of the solvents are methyl Cellosolve acetate, ethyl Cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, methyl lactate, ethyl lactate, 2-ethoxyethyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, cyclohexanone, methyl ethyl ketone, 2-heptanone, 1,4-dioxane, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethylene glycol monoisopropyl ether, etc.
The resist composition of the present invention comprises mainly the above-mentioned four components (i.e. (b) the cross-linking agent of the present invention, (c) the photoacid generator, (a) the aliphatic alkali-soluble polymer and (d) the solvent), and, if necessary, may further contain one or more UV-light absorbers such as 9-diazofluorene and its derivatives, 1-diazo-2-tetralone, 2-diazo-1-tetralone, 9-diazo-10-phenanthrone, 9-(2-methoxyethoxy)methyl anthracene, 9-(2-ethoxyethoxy) methyl anthracene, 9-(4-methoxybutoxy)methyl anthracene, 9-anthracene methyl acetate and benzophenone.
The resist composition may still further contain one or more sensitivity regulators [such as polyvinyl pyridine, polyvinyl pyridine/methyl methacrylate), pyridine, piperidine, triethylamine, tri-n-propylamine, tri-n-butylamine, trioctylamine, tri-benzylamine, dicyclohexylamine, dicyclohexylmethylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and N-methyl-2-pyrrolidone], plasticizers [such as diethyl phthalate, dibutyl phthalate and dipropyl phthalate]; organic acids [such as salicylic acid, lactic acid, 2-hydroxynaphthalene-3-carboxylic acid, 2-nitrobenzoic acid, phthalic acid, succinic acid and malonic acid] and surfactants [such as commercially available nonionic surfactants, cationic surfactants, anionic surfactants and fluorine type surfactants {such as one being put in the market under the trade names of Fluorad (a trade name, mfd. by SUMITOMO 3M Co., ltd.), EFTOP (a trade name, mfd. by TOHKEMPRODUCTS Corp.), SURFLON (a trade name, mfd. by Asahi Glass Co., Ltd.), Ftergent (a trade name, mfd. by Neos, Co., Ltd.), MEGAFAC (a trade name, mfd. by Dainippon Ink and Chemicals, Inc.) and UNIDYNE (a trade name, mfd. by DAIKIN INDUSTRIES, LTD.)}], which have conventionally been used in this technical field.
Formation of a pattern with the use of the resist composition of the present invention can be conducted, for instance, as follows.
The resist composition containing the cross-linking agent of the present invention is applied to a substrate for a semiconductor device such as silicon wafer to form a layer having a thickness of 0.3 to 2.0 xcexcm (when the layer is used as the top coat layer in three layers, the thickness is 0.1 to 0.5 xcexcm), and the resultant is prebaked at 70 to 130xc2x0 C. in an oven for 10 to 30 minutes or at 60 at 150xc2x0 C., preferably 60 to 110xc2x0 C. on a hot plate for 180 seconds.
Then, a mask for obtaining the desired pattern is placed over the thus obtained resist film and a deep UV-light having a wavelength of 220 nm or less is irradiated thereon at a dose of 1 to 100 mJ/cm2, followed by baking at 60 to 150xc2x0 C., preferably 80 to 110xc2x0 C. on a hot plate for 60 to 180 sec. Finally, development using 0.1 to 5% aqueous tetramethylammonium hydroxide (TMAH) solution or other alkaline developing solution is conducted on the resultant for 0.5 to 3 minutes by a dip method, a puddle method, a spray method or other conventional method, whereby the object negative pattern can be formed on the substrate.
The mixing ratio of the cross-linking agent of the present invention, the photoacid generator, the aliphatic alkali-soluble polymer is usually 1 to 30 parts by weight, preferably 1 to 20 parts by weight of the photoacid generator and 1 to 40 parts by weight, preferably 1 to 20 parts by weight of the cross-linking agent based on 100 parts by weight of the polymer. The amount of the solvent in the resist composition of the present invention is not specifically limited so long as application of the negative working resist composition obtained by dissolving the aliphatic alkali-soluble polymer and the photoacid generator to a substrate is not hindered. The amount of the solvent is generally within the range of 1 to 20 parts by weight, preferably 1.5 to 10 parts by weight per part by weight of the polymer.
The developing solution used in various processes for forming a pattern mentioned above is selected from an aqueous alkaline solution having such a suitable concentration as being capable of causing a large difference in solubility of the resist material between the exposed part and the non-exposed part in accordance with a solubility of a resist material used. The aqueous alkaline solution includes an aqueous solution containing an organic amine such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, choline, triethanolamine, morpholine, and 1-methylmorpholine, and an aqueous solution containing an inorganic alkaline compound such as sodium hydroxide and potassium hydroxide.
The substrate for a semiconductor device includes a silicon wafer, polysilicone, a TiN substrate, a BPSG substrate, an anti-reflective substrate, etc. The substrate is preferably treated previously with an agent for treating substrate such as hexamethyl disilazane (HMDS).
When an aliphatic alkali-soluble polymer containing a monomer unit represented by the formula [33] as a structural component is used as the polymer in the resist composition of the present invention, the following remarkable effect can be attained. Namely, the composition shows higher transmittance against deep UV-light as compared with polymers which have so far been used for the same purpose, and further a cross-linking reaction takes place in the presence of the cross-linking agent having high transmittance against deep UV-light, which is represented by the formula [1], [2] and/or [3] and the photoacid generator so that a good negative resist pattern is obtained after the alkaline development, resulting in making it possible to manufacture semiconductor devices having much highly integrated semiconductor integrated circuits.
It is recognized that an acid is generated by irradiation with any of a deep UV-light, KrF excimer laser beams, electron beams and soft X-ray to cause chemical amplification in the resist composition of the present invention by suitably selecting the photoacid generator. Therefore, the resist composition of the present invention can be said as one which can form a pattern using chemical amplification even by irradiation with a deep UV-light, KrF excimer laser beams, electron beams or soft X-ray at a low irradiation dose.
In the following, mechanism is explained in a case of the resist composition containing the cross-linking agent of the present invention. For instance, in the part exposed to a deep UV-light having a wavelength of 220 nm or less such as ArF excimer laser beams (xcex=193 nm), an acid is generated by a photo reaction shown by the following [equation 1], [equation 2], [equation 3], etc.
[Equation 1]
[Equation 2]
[Equation 3]
After the exposure process, the resultant is heated, whereby a cross-linking reaction is occurred between the hydrophilic group of the polymer of the present invention and the cross-linking agent containing 2 or more epoxy groups in the presence of an acid as illustrated in the [equation 4] so as to make the polymer alkali-insoluble.
[Equation 4]
On the other hand, in the part not exposed to light, no acid is generated and thus no chemical reaction takes place even by heating, and as a result, the polymer remains alkali-soluble. In this way, when a pattern formation is conducted with the use of the resist composition of the present invention, there is caused a difference in solubility in an alkaline developing solution between the part exposed to light and the part not exposed to light, and thus a well-contrasted negative pattern is formed.